Question

The blood group known as universal acceptor is

• A. A
• B. B
• C. AB
• D. O

Answer 1

Answer: (C)

Landsteiner recognized three kinds of blood group ie, $A,B$ and $O$, fourth and most rare $AB$ blood group was discovered by Von Decastello and Sturle (1902).

Blood group	Antigens in RBCs	Antibodies in Plasma	Can Donate to Groups	Can Receives from Groups
A	A	Anti -b	A, AB	O, A
B	B	Anti -a	B ,AB	O, B
AB	A and B	None	AB	Universal recipient
O	None	Anti-a and Anti -b	Universal donor	O

From the above table it is clear that the person of blood group $AB$ has both antigens, ie, $A$ and B but no antibodies in their plasma. Such person cannot donate blood to persons of other blood group but can receive from all, therefore called universal recipients.
The person of blood group $O$ has both antibodies and no antigen, therefore these person can donate blood to any person and, hence called as universal donors.